import os

from .sessions import (
    FileSystemSessionInterface,
    MemcachedSessionInterface,
    MongoDBSessionInterface,
    NullSessionInterface,
    RedisSessionInterface,
    SqlAlchemySessionInterface,
    SqliteSessionInterface,
)

__version__ = "0.6.0"


class Session:
    """This class is used to add Server-side Session to one or more Flask
    applications.

    There are two usage modes.  One is initialize the instance with a very
    specific Flask application::

        app = Flask(__name__)
        Session(app)

    The second possibility is to create the object once and configure the
    application later::

        sess = Session()

        def create_app():
            app = Flask(__name__)
            sess.init_app(app)
            return app

    By default Flask-Session will use :class:`NullSessionInterface`, you
    really should configurate your app to use a different SessionInterface.

    .. note::

        You can not use ``Session`` instance directly, what ``Session`` does
        is just change the :attr:`~flask.Flask.session_interface` attribute on
        your Flask applications.
    """

    def __init__(self, app=None):
        self.app = app
        if app is not None:
            self.init_app(app)

    def init_app(self, app):
        """This is used to set up session for your app object.

        :param app: the Flask app object with proper configuration.
        """
        app.session_interface = self._get_interface(app)

    def _get_interface(self, app):
        config = app.config.copy()

        # Flask-session specific settings
        config.setdefault("SESSION_TYPE", "null")
        config.setdefault("SESSION_PERMANENT", True)
        config.setdefault("SESSION_USE_SIGNER", False)
        config.setdefault("SESSION_KEY_PREFIX", "session:")
        config.setdefault("SESSION_ID_LENGTH", 32)

        # Redis settings
        config.setdefault("SESSION_REDIS", None)

        # Memcached settings
        config.setdefault("SESSION_MEMCACHED", None)

        # Filesystem settings
        config.setdefault(
            "SESSION_FILE_DIR", os.path.join(os.getcwd(), "flask_session")
        )
        config.setdefault("SESSION_FILE_THRESHOLD", 500)
        config.setdefault("SESSION_FILE_MODE", 384)

        # MongoDB settings
        config.setdefault("SESSION_MONGODB", None)
        config.setdefault("SESSION_MONGODB_DB", "flask_session")
        config.setdefault("SESSION_MONGODB_COLLECT", "sessions")

        # SQLAlchemy settings
        config.setdefault("SESSION_SQLALCHEMY", None)
        config.setdefault("SESSION_SQLALCHEMY_TABLE", "sessions")
        config.setdefault("SESSION_SQLALCHEMY_SEQUENCE", None)
        config.setdefault("SESSION_SQLALCHEMY_SCHEMA", None)
        config.setdefault("SESSION_SQLALCHEMY_BIND_KEY", None)

        common_params = {
            "key_prefix": config["SESSION_KEY_PREFIX"],
            "use_signer": config["SESSION_USE_SIGNER"],
            "permanent": config["SESSION_PERMANENT"],
            "sid_length": config["SESSION_ID_LENGTH"],
        }

        if config["SESSION_TYPE"] == "redis":
            session_interface = RedisSessionInterface(
                config["SESSION_REDIS"], **common_params
            )
        elif config["SESSION_TYPE"] == "memcached":
            session_interface = MemcachedSessionInterface(
                config["SESSION_MEMCACHED"], **common_params
            )
        elif config["SESSION_TYPE"] == "filesystem":
            session_interface = FileSystemSessionInterface(
                config["SESSION_FILE_DIR"],
                config["SESSION_FILE_THRESHOLD"],
                config["SESSION_FILE_MODE"],
                **common_params,
            )
        elif config["SESSION_TYPE"] == "mongodb":
            session_interface = MongoDBSessionInterface(
                config["SESSION_MONGODB"],
                config["SESSION_MONGODB_DB"],
                config["SESSION_MONGODB_COLLECT"],
                **common_params,
            )
        elif config["SESSION_TYPE"] == "sqlalchemy":
            session_interface = SqliteSessionInterface(
                app,
                config["SESSION_SQLALCHEMY"],
                config["SESSION_SQLALCHEMY_TABLE"],
                config["SESSION_SQLALCHEMY_SEQUENCE"],
                config["SESSION_SQLALCHEMY_SCHEMA"],
                config["SESSION_SQLALCHEMY_BIND_KEY"],
                **common_params,
            )
        else:
            session_interface = NullSessionInterface()

        return session_interface